In general, a motor is a device that converts electrical energy into mechanical energy to provide a rotational force. Motors are being widely applied to various industrial fields including electric home appliances and industrial machines. Motors can be largely divided into alternating current (AC) motors and direct current (DC) motors.
An inductor motor, which is one type of the AC motors, generates a rotational force by reciprocal reactions between magnetic fluxes, which are produced when AC current flows through a coil wound around a stator, and induction current produced at a rotor inserted into the stator.
With reference to FIG. 1, a conventional induction motor will be descried hereinafter.
FIG. 1 illustrates a top view of a conventional induction motor. A conventional induction motor 10 includes a stator 11, a coil 12 and a rotor 13. The stator 11 is affixed to a casing or a shell (not shown). The coil 12 is wound around the stator 11. The rotor 13 is installed to be rotatable by having a gap inside the stator 11.
The stator 11 is formed by stacking a plurality of silicon steel sheets having the same shape. Although not illustrated, an opening is formed inside the stator 11 to allocate the rotor 13 therein. Teeth 11b are formed to be spaced a certain distance apart from each other along the inner surface of the stator 11, and a plurality of slots 11a are formed between the respective teeth 11b. 
The coil 12 is wound around the individual teeth 11b so as to supply AC current, and rotating magnetic fluxes is generated due to the aforementioned structure of the stator 11.
As described above, the rotor 13 is installed to be rotatable by having the gap inside the stator 11, and a shaft 13a passes through a central part of the rotor 13 to be firmly affixed to the rotor 13. Along an edge region of the rotor 13, a plurality of bar-type conductors 13b are inserted into and affixed to the rotor 13. Barriers 13c are formed around the shaft 13a. A plurality of permanent magnets 13d is inserted into each of the barriers 13c. 
The shaft 13a is installed to be rotatable by means of bearings of the casing or shell (not shown), which is a frame of the induction motor 10.
The conductors 13b are usually made of aluminum (Al) having excellent electrical conductivity and allowing a die casting method.
The barriers 13c are formed in a shape of circular arcs, and are paired up in a manner to face each other by having the shaft 13a therebetween. The inner side of each of the barriers 13c is filled with air to shield the magnetic fluxes.
The permanent magnets 13d are inserted into each of the barriers 13c and affixed to the individual barriers 13c by being pressed into the inside of the individual barriers 13c. The permanent magnets 13d produce a torque by reciprocally reacting with a magnetic field generated at the coil 12.
In operation, when a certain amount of current is supplied to the coil 12, a rotating magnetic field, generated due to the structure of the stator 11, and the induction current, generated at the conductors 13b of the rotor 13, reciprocally react with each other. As a result, the rotor 13 starts rotating. When the rotor 13 reaches a certain synchronous speed, both the torque, produced by the permanent magnets 13d, and a reluctance torque, produced due to the structure of the rotor 13, cause the rotor 13 to rotate.
However, in the conventional inductor motor 10, since the permanent magnets 13d need to be inserted forcely into the respective barriers 13c, the permanent magnets 13d are likely to be damaged due to friction between the two metals during the assembly. Also, the assembly of the permanent magnets 13d may be complicated.
Moreover, as illustrated in FIG. 1, the barriers 13c are formed to have the circular arcs. There may be the loss of the magnetic fluxes Mloss that prevents the torque production because the magnetic fluxes pass through a space between the barriers 13c. As a result, efficiency of the conventional inductor motor 10 may be reduced to a great extent.
Accordingly, it is necessary to develop an inductor motor that can make it easy to install the permanent magnets 13d into the individual barriers 13c, improve productivity, and minimize the loss of the magnetic fluxes so as to improve the efficiency of the induction motor.